The control of insects has been a problem long before mankind conceived of a patent system. While segments of the world are burdened with significant insect control problems from a variety of insect types, many of the world's most populated centers have found it particularly difficult to control the mosquito population. In the United States, for example, monies may not be expended in certain locations to control flies, but it is known that effective control of the food supply for flies in metropolitan areas will significantly reduce the nuisance caused by this insect. As increased emphasis is place on outdoor recreation, more effective methods are required for controlling the types of insects most commonly encountered by the largest number of people. One of the more troublesome, if not the most troublesome, insect that people desire to control is the mosquito. A great deal of effort is expended annually by municipalities to combat the high mosquito population, but these efforts seem to have limited benefits. As increased emphasis is placed on outdoor recreation, more effective methods of controlling mosquitos are required. Within the past decade, there is also increased medical evidence that certain species of mosquitos carry and transmit to humans a variety of diseases.
Various techniques have been proposed for controlling one animal variety, but these techniques have generally been found to be ineffective for other animals. U.S. Pat. No. 4,105,992, for example, discloses a technique utilizing a recording of young rodents to attract mature female rodents to a site, but this technique, even if effective, would not appear to be applicable to controlling insects. Various acoustic attractants have been proposed to attract fish to a lure and/or to a particular fishing site. U.S. Pat. No. 2,577,229 discloses an audible fish lure to produce a sound simulating insects on which the fish feeds. U.S. Pat. No. 2,977,705 discloses an acoustic fish attractant for carnivorous fish. U.S. Pat. No. 3,414,873 discloses another fish attractant that simulates turbulence and vibratory sounds generating by injured or struggling fish to attract predatory fish. None of these patents would appear, however, to provide any teaching with respect to an effective technique to control the insect population.
Probably the most widely used and one of the oldest insect attractants is based on the concept of attracting insects to a particular site by illumination. Most illumination-based attractant devices kill the attracted insect by electrocution, although other concepts have been successfully used to kill the attracted insects. An early patent disclosing an illumination attractant device is U.S. Pat. No. 1,982,123. While illumination-based insect attractants are quite successful for certain insects, such as beetles and moths, these devices are not particularly useful for attracting mosquitos. U.S. Pat. No. 2,861,132 discloses a technique for attracting various insects, and particularly for attracting mosquitos, based on the sounds of the female gender that attract the male gender. While this technique may be useful for interrupting the life cycle of various insects, it has not been proven successful in controlling the mosquito population. Also, while research has shown that certain species of male mosquitos can become sexually stimulated with a tuning fork pitched to a certain frequency, it is generally known that the female mosquito, not the male mosquito, draws blood from animals and is thus the mosquito that is most desirably controlled. Further information regarding acoustic sounds for sexually exciting a male mosquito are disclosed in Grzimek's Animal Life Encyclopedia, Volume 32, page 478.
U.S. Pat. No. 3,937,826 discloses a technique for visually attracting certain insects, such as a fly, in order to kill the attracted insect. This technique has not proven commerically successfully, however, for controlling the mosquito population. U.S. Pat. No. 4,168,591 discloses a technique that utilizes a combination of heat and moisture for attracting insects. While the disclosure of this patent indicates that this technique is applicable to various insects, it particularly suggests that the technique is effective to attract mosquitos. Again, however, this technique has not proven to be commerically successful at attracting insects, and has contributed to the plethora of confusion regarding reasons insects are attracted to humans. U.S. Pat. No. 4,506,473 discloses a technique for attracting blood-sucking insects based upon the release of carbon dioxide. This patent similarly has not proven to be commercially successful at attracting insects, and has further confused the public regarding the basis for the attraction of mosquitos to humans.
In spite of the extensive efforts of individuals and companies to devise a technique for successfully attracting and killing mosquitos, it should be readily apparent that none of the techniques disclosed in the above patents have met with significant commercial success. Most of the effort expended by municipalities to control the mosquito population concerns clean-up efforts and/or the spraying of chemicals on stagnant bodies of water. No matter how much effort is expended in reducing the number of tires, cans, and similar receptacles that have mosquito eggs, it is virtually impossible to eliminate the habitat where mosquito eggs will hatch. Also, it has been shown that at least some species of mosquitos do not require water to successfully serve as the habitat for eggs, and that mosquitos can be hatched from eggs deposited in ground cracks containing very little moisture. Nevertheless, millions of dollars are expended by municipalities to spray storm sewers, ditches, ponds and similar locations with chemicals designed to reduce the mosquito population. While the spraying of these chemicals produces questionable benefits, this spraying technique is expensive, and chemically contaminates the air and/or ground water.
The disadvantages of the prior art are overcome by the present invention, and improved methods and apparatus are hereinafter disclosed for attracting insects to a particular site. According to a preferred embodiment of the invention, mosquitos are attracted to a particular site by acoustic sounds, and the attracted mosquitos are killed with conventional equipment.